Brake mechanism



April 25, 1944.

4 BERNO 2,347,239

BRAKE MECHANISM Filed, Jan. 5, 1941 2 Sheets-Sheet 2 /O4 INVENTOR E'Dwqiao F1. Erremo Patented Apr. 25, 1944 UNITED STATES PATENT OFFICE BRAKE MECHANISM Edward H. Berno, Plymouth, Mich.

Application January 3, 1941, Serial No. 373,017

Claims.

. construction which may be used both in the master cylinder and in the wheel brake cylinders of a hydraulic braking system, such as that illustrated herein.

Another object of my invention is to provide a new and improved form of master cylinder construction for hydraulic brake systems.

Other objectsand advantages of my invention will be apparent from consideration of the following specification taken in conjunction with the accompanying drawings, of which there are two sheets, and wherein:

Fig. 1 is an elevational view of a wheel brake mechanism embodying one form of my inventlon:

Fig. 2 is a sectional view taken in a plane along the line 2--2 of Fig. l;

Fig. 3 is a view, partly in section, of a master cylinder construction embodying my invention;

Fig. 4 is an elevational view of a modified form of a wheel brake mechanism embodying my invention; and

Fig. 5 is a section taken in a plane along the line 55 of Fig. 4.

Referring now to Figs. 1 and 2, there is illustrated a wheel brake assembly of a motor vehicle and which, as shown, consists of a conventional brake drum I 0 which is rotatable with a road wheel of the vehicle, a backing plate l2 which is non-rotatably supported by the vehicle chassis, a

pair of brake shoes I4 and i6, an actuating link or lever l8, an adjustable link 20, a wheel cylinder and piston assembly 22, and a pair of anchor pins 24 and 26. The anchor pins 24 and 26 are rigidly secured to the backing plate I2, as illustrated in Fig. 2' in connection with pin 26, for taking the braking torque of the shoes 14 and IS. The shoe I4 is provided with an enlarged hole or slot 28 in one end thereof and through which the pin 24 extends for taking the torque of the shoe l4 upon braking when the drum I0 is rotating in the direction indicated by the arrow in Fig.

1. The shoe l6 likewise is provided with an enlarged hole or slot 30 in one end thereof and through which the anchor pin 26 extends for taking the torque of the shoe l6 when the drum I0 is rotating in the direction indicated by the arrow in Fig. 1. The link or actuating leve'r I8 is connected at its center 32 to the center 34 of the shoe H, the shoe being provided with a rounded lug which seats in a complementary shaped socket formed in the link l8 so that braking effort applied to the shoe will be applied radially and at the center of the shoe thereby obtaining substantially uniform pressure between the drum and the brake lining carried by the shoe l4 and throughout the entire extent of the lining. The shoe l6, assembly 22, and links l8 and 20 comprise links or parts of a linkage system for applying the brakes. The shoes I4 and I6 each are provided with brake lining I! for braking movement of the drum. The shoes 14 and I6, due to the manner in which they are connected to the supporting plate l2, are floating shoes.

The expression drum braking means as used in the claims necessarily includes the brake lining and in some cases also includes the brake shoe to which the lining is afiixed.

One end 36 of the link I8 is seated against one end 38 of the adjusting link 20 and the other end of the adjusting link 20 is shaped so as to seat in a notch formed in one end 40 of the shoe 16. The adjusting link 20 comprises two parts 42 and 44 which are .threadedly secured together so that the length of the link 20 may be adjusted, which, when the link 20 is assembled as illustrated in Fig. 1, may be accomplished by turning the notched wheel 46 formed on the part 42. The other end 48 of the link I8 is seated in a seat 58 provided at one end of a floating cylinder 52.

The floating cylinder 52 comprises a part of the wheel brake cylinder and piston assembly 22 which further includes a piston 54 mounted for reciprocation within the bore of the cylinder 52. The rear end 56 of the piston is shaped so as to form a seat for the end 58 of the brake shoe I6. The bore of the cylinder 52 is relieved by an annular groove 60 in which a U-shaped annular resilient gasket 62 is arranged so as to provide a seal between the piston 54 and the cylinder 52. The groove 60 is somewhat larger in cross section than the gasket 62 and the open side of the gasket is so arranged as to be open toward the pressure side of the cylinder. In this manner fluid under pressure admitted into the cylinder through the connection 64 will act on the gasket 62 so as to force the sides thereof into sealing 2 contact both with the outer wall of the piston and efiect relative movement between when there is no I to the eye 12 and at with the inner wall of the groove and will also the piston 54 and the cylinder 52 for applying pressure to the brake shoes. I

The cylinder 5 is bifurcated to form arms 66 in which aligned slots 88 are provided. As will be observed, the arms 58 straddle the end 58 of the shoe I9 and the pin 28 extends through the slots 88 in the arms 66 as well as through the slot 30 in the shoe I8. Springs 10 connected to the shoes I4 and I6 serve to maintain the brake shoes away from the drum I pressure in the fluid system. One of the arms 69 is provided with an eye 12 and a spring 14 connected at one end thereof the other end thereof to an opening 18 in the shoe I6 serves to hold the cylinder and piston assembly 22 and the brake shoe IS in the position illustrated in Fig. 2 with respect to the pin 26 when the system is at rest. During rotation of the drum I0 in the direction indicated by the arrow in Fig. 1 and upon application of pressure to the fluid in the cylinder and piston assembly 22, the piston 54 and cylinder 52 will move relative to each other until the shoes I4 and I8 come into contact with the rotating drum whereupon, due to mutation of the drum, the end 58 of the shoe I will seat against the pin 26 as illustrated in Fig. 2. The relative movement between the cylinder and piston will result in th application of pressure to the end 48 of the link I8. As soon as the shoe I4 comes in contact with the 38 of the link I8 will transmit through the link 20 and to the end 40 of the shoe I8 a force equal to that applied to the end 48 of the link I8 by the cylinder 52. The pin 24 will take the braking torque of the shoe I4 while the pin 26 will take the braking torque of the shoe IS. The braking pressure and effect of each of the shoes will be the same. When the drum is rotating in the opposite direction, the braking torque of both shoes will be taken by the anchor pin 28.

Fluid under pressure may be supplied to the wheel cylinder and piston assembly through the connection 64 from a master cylinder, such as that illustrated in Fig. 3, the construction of which comprises a cylinder 80, a piston 82, a fluid reservoir 84, a piston actuating rod 88, a spring 98 for returning the piston to its retracted position, a rubber or non-metallic valve member 90, a spring 92 for biasing the valve member 90 to its seat 93, a coupling member 94 to which connection 84 is connected by tubing, a bleed 96, valve members 81, 95, and I02, and valve spring IOI. Valve seat 93 comprises an annular face formed on the end of the cylindrical boss I05, and when annular valve member 90 is seated thereon the fluid inside of boss 'I05 is separated from except as hereinafter noted. Valve member 90 carries an apertured wall or partition which forms another valve member 95 cooperating with which is a valve member 81 carried by one end of stem 99 which extends through the apertured valve member 95. On the other end of stem 99, valve member I02 is provided which is adapted to cooperate with valve seat I04 for closing communication through duct I00 between the reservoir 84 and cylinder 80.

The interior of the boss I05 communicates with coupling member 94 which leads to the wheel cylinders, Valve members 81 and 95 normally are held seated by spring I0! which is confined between valve members I02 and 95. Valve 90, 93 normally is held closed by spring 92 but will open to permit return of fluid from the lines drum the other end the fluid in cylinder 80,

to the cylinder whenever the pressure in the lines is greater than the pressure of spring 92. The piston 82 is slidably mounted in cylindrical bearing surfaces 91 and and U-shaped annular resilient gasket 9| arranged in an annular groove in the cylinder 80 and around the piston 82 is adapted to provide a seal between the piston 82 and the cylinder 80 upon relative movement therebetween. Another gasket I01 arranged around a part of the piston 82 may be provided to seal the joint between the piston and the casing which forms the reservoir 04. Normally the wheel cylinders, of which there is one for each wheel brake assembly, and the connection between the same and the master cylinder, and the master cylinder are maintained full of fluid, such as a liquid. When the piston 82 is in itsretracted position the duct I00 is open but when the piston 82 moves a little to the left of the position in which it is illustrated in Fig. 3', valve member I02 is adapted to cooperate with the seat I04formed on the piston 82 to close the duct I00. Furthermovement of the piston 82 to the left will open valve 81, and subject the fluid in the cylinder, in the connections to the wheel brake cylinders, and in the wheel brake cylinders, to pressure for the purpose of effecting the application of the brakes. The gasket 9| is arranged relative to the piston 82 and the cylinder 80 so that upon application of pressure to the fluid in the cylinder 80 the side walls of the gaskefwill be forced into sealing engagement with the adjacent walls of the cylinder and of the piston. The rod 88 may be arranged to be actuated by a conventional foot brake pedal.

Referring now to Figs. 4 and 5, there is illustrated a modified form of construction which comprises a backing plate II2, a conventional drum IIO, a pair of brake shoes H4 and H5, springs H8 for holding the same in a retracted position, a wheel cylinder and piston assembly I20, and a series of links I22, I24, and I26 which are arranged for actuating the shoes H4 and H5 and connected to the wheel cylinder and piston assembly or link I20 for actuation thereby. The shoe 4 has pivotally connected to the center I30 thereof one end of a link I26, the other end of which is pivotally mounted upon an anchor pin I28 carried by the backing plate H2. The link I22 at its center is also connected at I30 to the center of the shoe II4 for applying pressure thereto. One end I32 of the link I22 is pivotally connected at I33 to an arm I34 provided on the cylinder of the wheel cylinder and piston assembly I20, while the other end I36 of link I22 is pivotally connected at I31 to one end of the link I24. The link I22 is provided with a slot I40 through which the pin I28 extends, the slot I40 being of suflicient size so as to permit unrestricted movement of the link I22 by the wheel cylinder and piston assembly; The pin I28 may carry a collar I42 (Fig. 5) secured in place by a cotter pin I44 for securing the assembly to the backing plate H2. The other end of the link I24 which is of adjustable length is pivotally connected at I45 to one end of the link I25. The link I26 is pivotally secured to an anchor pin I48 carried by the backing plate and at I50, which is the center of the link I26, the same is pivotally connected to the center of the brake shoe H6. The anchor pin I48 thereby takes the braking torque of the braking shoe HE.

A piston of the wheel cylinder and pistonassembly is provided with an arm I52 which is pivotally connected at I54 to one end of the link I26 so that the anchor pin I48 takes the reaction of the wheel cylinder and piston assembly upon application of the brakes. The construction of the wheel cylinder and piston assembly may be of any desired design and hence has been shown somewhat diagrammatically. When the drum III) is rotated in the direction indicated by the arrow in Fig. 4, operation of the wheel cylinder and Piston assembly I20 will expand the linkage I22, I24, and I26 and will thereby move the shoes H4 and H6 into operative engagement with the drum III]. Due to the arrangement of the linkage with respect to the anchor pins I28 and I48 and the manner in which the linkage is connected to the brake shoes, the same amount of braking force will be exerted by each shoe whether the drum is rotating forwardly or reversely.

While the invention has been described with some detail, it is to be understood that the description is for the purpose of illustration only and is not definitive of the limits of the inventive idea. The right is reserved to make such changes in the details of construction and arrangement of parts as will [all within the purview of the attached claims.

I claim:

1. Brake mechanism comprising a drum, a

backing plate, an anchor pin carried thereby, a

pair of links each of which is secured to said anchor pin in such a manner as to have a limited sliding movement relative thereto, drum braking means operatively associated with one end of one of said links so as to be actuated thereby, a connection between said drum braking means and the free end of the other of said links, drum brak-' ing means operatively associated with said other of said links, one of said links comprising a cylinder and piston assembly including a cylinder member and a piston member, one of said members being arranged relative to said other of said links so as to move therewith and the other of said members havinga pin and slot connection with said anchor pin and being arranged between said pin and said first mentioned drum braking means.

2. Brake mechanism comprising a drum, a backing plate, an anchor pin carried thereby, a cylinder and piston assembly comprising a piston member and a cylinder member, one of said members being secured to said pin in such a manner as to have a limited sliding movement relative thereto and the'other of said members being arranged between said pin and said one of said members, drum braking means operatively associated with one of said members so as to be actuated thereby and other drum braking means connected to the aforesaid drum braking means and to the other of said members so as to be actuated thereby.

3. Brake mechanism comprising a drum, a backing plate, an anchor pin carried thereby, a cylinder and piston assembly comprising a piston member and a cylinder member, one of said members being secured to said pin in such a manner as to have a limited sliding movement relative thereto and the other of said members being arranged between said pin and said one of said members, drum braking means operatively associated with one of said members so as to be ver, said shoe having an aperture in one end having a seat adapted to engage and be seated against said anchor pin during braking in one direction of rotation of said drum.

4. Brake mechanism comprising a brake drum, a backing plate, a pair of links, each of which is anchored to said pin in such a manner as to have a limited sliding movement relative thereto, a lever, one end of which is pivotally connected to one shoot one of said links, a connection between the other end of said lever and the free end of the other of said links, said other of said links having drum braking means operatively associated therewith, and other drum braking means operatively associated with said lever so as to be actuated thereby, one of said links being extensible for moving said drum braking means into operative engagement with said drum.

5. Wheel brake structure comprising a brake drum, a supporting plate, an anchor pin carried by said plate, a plurality of links connected together. one of which includes a brake shoe. one of which is pivotally connected at its center to a second brake. shoe and another of which links is extensible for moving said shoes into operative engagement with said brake drum, said extensible link being arranged between said pin and one end of said second mentioned link, and having a pin and slot connection with said anchor pin.

6. Wheel brake structure comprising a drum, a. backing plate, an anchor carried by said plate, an extensible link comprising a hydraulic cylin der and piston assembly having one end thereof pivotally connected to said anchor, a lever pivotally connected at one end thereof to the other end of said extensible link, a second link having a pivotal connection at one end thereof with said anchor and connected at the other end thereof to the other end of said lever. drum braking means operatively associated with said second link, and other drum braking means com prising a brake shoe having a pivotal connection at the center thereof with the center of said lever, a second anchor carried by said plate and a connection between said anchor and said shoe which permits movement of said shoe into and out of engagement with said drum and which transmits the braking torque of said shoe to said second anchor.

'7. Wheel brake structure comprising a drum, a backing plate, an anchor carried by said plate, an extensible link comprising a hydraulic cylinder and piston assembly having one end thereof pivotally connected to said anchor, a lever plvotally connected at one end thereof to the other end of said extensible link, a second link having a pivotal connection at on end thereof with said anchor and connected at the other end thereof to the other end of said lever, drum braking means operatively associated with said second link, and other drum braking means comprising a brake shoe having a pivotal connection at the center thereof with the center of said lethereof and a second anchor carried by said plate and having a loose fit in said aperture for taking the torque of said shoe.

8. Wheel brake structure comprising a drum, a backing plate, an anchor carried by said plate, an extensibl link comprising a hydraulic cylinder and piston assembly having one end thereof pivotally connected to said anchor, a lever pivotally connected at one end thereof to the other end of said extensible link, a second link having a pivotal connection at one end thereof with said anchor and connected at the other end thereof to the other end of said lever, drum braking means operatively associated with said second link, and other drum braking means comprising a brake shoe having a pivotal connection at the center thereof with the center of said lever, a second anchor carried by said plate and a link pivotally connected at one end thereof -to the center of said shoe and at the other end thereof to said second anchor.

9. Wheel brake structure'comprising a drum, a backing plate, an anchor carried by said plate, an extensible link comprising a hydraulic cylinder and piston assembly having a cylinder member and a piston member, one of said members being connected to said anchor in such a manner as to have a limited sliding movement relative thereto, the other of said members being arranged between said anchor and said one of said members, a lever pivotally connected at one end thereof to said one of said members, a second link having a pivotal connection at one end thereof with said anchor and connected at the other end thereof to the other end of said lever, drum braking means operatively associated with said second link and other drum braking means comprising a brake shoe having a pivotal connectlon at the center thereof with th center of said lever.

10. Wheel brake structure comprising a drum, a backing plate, an anchor carried by said plate, an extensible link comprising a hydraulic cylinder and piston assembly having a cylinder member and a piston member, one of said members being connected to said anchor in such a manner as to have a limited sliding movement relative thereto, the other of said members bein arranged between said anchor and said one of said members, a lever pivotally connected at one end thereof to said one of said members, a second link having a pivotal connection at one end thereof with said anchor and connected at the other end thereof to the other end of said lever, drum braking means operatively associated with said second link and other drum brakin means comprising a brake shoe having a pivotal connection at the center thereof with the center 

